Laboratory equipment with flammable refrigerant

Abstract

The invention relates to a laboratory device with a flammable refrigerant and to a method for operating such a laboratory device and to a method for manufacturing such a laboratory device. The laboratory device with a flammable refrigerant provided by the invention has an electrical connection for providing electrical energy for the laboratory device, an electrical switching device, a sequence controller and a monitoring device for monitoring the electrical switching device. The invention improves the operating safety of a refrigerated laboratory device with a flammable refrigerant, at least temporarily avoids and preferably excludes the formation of ignition sparks within the device which can ignite the flammable refrigerant, at least in critical operating phases.

Description

Technical Field

[0001] The present invention relates to a laboratory device having a flammable refrigerant, a method for operating such a laboratory device, and a method for manufacturing such a laboratory device. Background Technology

[0002] Refrigerated laboratory equipment, especially laboratory devices or apparatus such as refrigerated laboratory centrifuges or laboratory refrigerators, must meet various safety requirements. For example, the DIN EN 61010-2-011 standard specifies safety requirements for electrical measurement, control, regulation, and laboratory equipment. In particular, it should be ensured that the design and construction of refrigeration equipment provides adequate protection for users, bystanders, trained service personnel, and the surrounding area from any special hazards that may arise from the refrigeration system.

[0003] DIN EN 378 considers the life cycle of refrigeration facilities, particularly regarding facility / equipment safety, but also takes into account factors such as the area where the facility is located, refrigerant limits, and personnel protection in cold spaces. This standard specifically addresses the flammability ratings of refrigerants as defined in ISO 817: 1 (no flame propagation), 2L (low flammability), 2 (flammable), and 3 (highly flammable). Examples of refrigerants include: propane, (iso)butane (flammability rating 3); R152a (flammability rating 2); R1234yf (flammability rating 2L); R410A, R22 (flammability rating 1). In this specification, the terms flammable and combustible are used synonymously.

[0004] Highly flammable hydrocarbons, particularly propane and (iso)butane, have favorable environmental properties. For example, the aforementioned refrigerants have an ozone depletion potential (“ODP”) of 0 and a global warming potential (“GWP”) or carbon dioxide equivalent of only three.

[0005] In modern refrigerated laboratory equipment, the use of refrigerants with favorable environmental properties is desirable. Regarding the aforementioned refrigerants propane and (iso)butane, additional safety precautions are necessary. Safe spaces within the machinery or equipment are particularly important. These spaces must remain safe even in the event of a leak, damage, or malfunction, provided that flammable refrigerant has escaped from the containers and wiring provided for them. Summary of the Invention

[0006] This invention addresses the technical problem of improving the operational safety of refrigerated laboratory equipment using flammable refrigerants. In particular, another technical problem upon which this invention is based is to temporarily avoid, and preferably eliminate, the formation of ignition sparks within the equipment that could ignite the flammable refrigerant, at least during critical operational phases.

[0007] Specifically, it can be stipulated that, upon initial operation of the laboratory equipment, the internal areas should first be ventilated by fans to expel any potentially flammable refrigerant from the internal areas, particularly to the surrounding environment. The ventilated internal areas are especially prone to generating ignition sparks. The formation of ignition sparks should be prevented until it can be assumed that no more flammable refrigerant remains in the internal areas. This can be achieved, in particular, by disconnecting the electrical components within the equipment from the power supply network. Therefore, the equipment preferably has electrical connections, with all potential current-carrying lines individually disconnected from the power supply network via at least one electrical switch. An exception might be the protective conductor and / or grounding wire. However, all phase and neutral conductors can preferably be individually disconnected from the power supply network via at least one electrical switch.

[0008] If it can now be assumed that even when the equipment is powered on, any ignition sparks that occur will not ignite a flammable mixture with a flammable refrigerant, then the connection process can be initiated. On the other hand, the connection should be reliable during this process, and the availability of power should be reliably monitored after connection. This reduces the likelihood of ignition sparks occurring after power is switched on, for example, in the event of an unexpected power outage, followed by immediate restoration of power. Alternatively or additionally, by monitoring the presence of power, laboratory equipment can also be operated in such a manner after being switched on that ignition sparks are avoided or only occur when a flammable mixture cannot be ignited.

[0009] Therefore, if the operating voltage between the wires in laboratory equipment can be reliably determined, operational safety can be improved, particularly regarding ventilation in at least the internal areas of the equipment. Furthermore, this detection can be used to ensure the safety of the process of powering on the equipment.

[0010] When an electrical operating voltage exists between the first (electrical) contact and the second (electrical) contact, it is recommended to determine the on / off state of the electrical switch and signal this state. Here, the first contact is located on the device side of the electrical switch (i.e., when the switch is off, the switch separates the first contact from the power supply network), and the second contact is connected to a different potential on the power supply side than the electrical grid. "Power supply side connection" means that during the process of connecting the device, the second contact is not isolated from the power grid by switches present in the various power supply lines of the device. Specifically, such another switch is located on the device side of the second contact.

[0011] In this way, the electrical operating voltage on the equipment side of the monitored electrical switch can be reliably determined because it does not depend on the switching state of other electrical switches on the equipment side of the second contact in the power supply line. It cannot be ruled out that the existence of the electrical operating voltage depends on the switching state of another switch, i.e., the switch located on the power supply side of the second contact, such as the main switch. However, during the connection process, such a main switch may be connected first, so the state during this process is equivalent to the case where there is no main switch.

[0012] If a signal is sent indicating that the monitored electrical switch is in a state that is not the expected state, then a signal can be sent and appropriate measures can be taken. Specifically, the presence or absence of an electrical operating voltage can be signaled to the sequence controller of the laboratory equipment. The sequence controller is configured to turn on and / or off at least two electrical switches of the laboratory equipment's electrical switching device. At least one corresponding sequence of controller actions (i.e., a control process with more than one action) executed by the sequence controller requires at least one switch to be turned on and / or off. Particularly in the case of a single-phase power supply for the laboratory equipment, two switches may exist and can be controlled by the sequence controller, one in the single-phase line and one in the neutral conductor. In the case of a multi-phase power supply, there may be one switch in each phase line and one switch in the neutral conductor (if any). In the case of a delta circuit, there is no neutral conductor. Optionally, not only can one switch be located in at least one line, but at least one additional switch can be connected in series. This additional switch can also be controlled by the sequence controller.

[0013] The intended state of the switches is generated, in particular, by a process controlled by a sequence controller. For example, if two electrical switches are to be turned on, the process assumes that both switches are initially closed. Therefore, at this stage of the process, a signal indicating the closed state is expected. Preferably, the process is configured to turn the switches on sequentially. If the switch is connected to the neutral conductor of the power supply on the power side, then if there is a clear and unchangeable assignment of the switch and the power supply wiring, that switch is preferably turned on first. For example, if the laboratory equipment has a connecting cable with a plug that can be inserted into a socket such as a single-phase power supply network in Germany, then this unchangeable assignment does not exist.

[0014] Therefore, the sequence controller can first check whether a switch is in the expected state based on a signal sent to it regarding the switch's status. If so, the next step in the process is for the sequence controller to turn on this switch and then check whether the switch is on using the signal sent to it. The sequence controller can then proceed to turn on another switch, where it checks whether the other switch is in the expected off state based on the signal sent to it before turning it on. Once turned on, the sequence controller can use the signal transmitted to it to check whether the other switch is on.

[0015] In this embodiment, the sequence controller must turn on two switches. In this case, and if only one or more switches will be turned on, it is preferable, as mentioned above, that the sequence controller checks whether a switch was still closed by means of information transmitted to it regarding the state of the switch before the corresponding switch was turned on. Furthermore, the sequence controller can check whether a switch is on after it has been turned on using a signal transmitted to it. As already mentioned, the signal can be a permanently existing signal, such as a signal with a defined signal level. However, the signal can also be a signal that exists only intermittently. In this case, the sequence controller, for example, records the reception of the signal and then infers the corresponding switch state over a future period of time. No state change at the signal input of the sequence controller can also be a signal. For example, the on state of a switch can be signaled by the presence of a corresponding signal at the assigned signal input of the sequence controller, either once, repeatedly, or permanently. If such a signal is not present, the sequence controller can determine that the switch is off. Preferably, in this case, the corresponding signal is permanently present at the signal input of the sequence controller assigned to that switch in the on state. If this signal is not present, or in another embodiment if a corresponding other signal is present, this means for the sequence controller that the switch is on. The continuous and uninterrupted signal transmission of the corresponding switch state or at least one of the two switch states increases security during monitoring and thus also increases the security of laboratory equipment operation.

[0016] After one or more switches are successfully turned on, the sequence controller can output a signal. This signal can be a prerequisite for starting the operation of at least one power supply of the laboratory equipment.

[0017] Therefore, a crucial process for the safety of laboratory equipment is the power-on process, which must be performed at the start of operation. However, this process can also be performed after operation has begun, for example, if there is a temporary power outage. Specifically, during the power-on process, a sequence controller controls the switching of electrical switches to generate power. However, this does not preclude the sequence controller from switching on and / or off at least one switch during operation of the laboratory equipment. When we say that the sequence controller switches on or off a switch, it means that the sequence controller performs the corresponding control procedure. For example, at least one switch may be configured as a relay, and the sequence controller controls the relay by activating or deactivating the relay's control circuitry.

[0018] If the sequence controller is now signaled to an undesirable state of at least one of the switches, then the sequence controller can prevent the operation of the laboratory equipment. In particular, it can directly shut off at least one of the electrical switches it can control, and preferably shut off all electrical switches supplying power to the laboratory equipment.

[0019] Specifically, a laboratory device containing a flammable refrigerant is provided, wherein the laboratory device has:

[0020] - An electrical connection for providing power to laboratory equipment, wherein the laboratory equipment can be connected to at least two different potentials in a power supply network for its operation.

[0021] - The electrical switching device has a first electrical switch for electrically separating from a first potential of the at least two different potentials and a second electrical switch for electrically separating from a second potential of the at least two different potentials.

[0022] - A sequence controller configured to turn on the first electrical switch and the second electrical switch.

[0023] - A monitoring device for monitoring electrical switching equipment, wherein the monitoring device is connected to a first electrical switch via a first contact on the equipment side and to a different potential from the first potential via a second contact on the power supply side.

[0024] The monitoring device is configured to determine the on / off state of the first electrical switch when an electrical operating voltage exists between the first contact and the second contact, and to notify the sequence controller of this state signal.

[0025] The sequence controller is configured to,

[0026] - When the first electrical switch is expected to be closed, but the monitoring device sends a signal indicating the first electrical switch is on, or

[0027] -When the first electrical switch is expected to be turned on, but the monitoring device sends a signal indicating that the first electrical switch is in the off state,

[0028] Prevent the operation of the laboratory equipment.

[0029] In addition, a method for manufacturing laboratory equipment containing a flammable refrigerant is specifically proposed, wherein the monitoring device and the sequence controller are designed as described above regarding the laboratory equipment.

[0030] Furthermore, a method for operating laboratory equipment with a flammable refrigerant is proposed, wherein the laboratory equipment has the aforementioned characteristics, wherein when an electrical operating voltage exists between a first contact and a second contact, a monitoring device determines the on / off state of a first electrical switch and notifies a sequence controller of this state signal, and wherein the sequence controller...

[0031] - When the first electrical switch is expected to be closed, but the monitoring device sends a signal indicating the first electrical switch is on, or

[0032] -When the first electrical switch is expected to be turned on, but the monitoring device sends a signal indicating that the first electrical switch is in the off state,

[0033] Prevent the operation of laboratory equipment.

[0034] Operating voltage is understood as the voltage supplied to operate laboratory equipment or at least one electrical device of the laboratory equipment (e.g., a centrifuge drive motor), or at least sufficient to operate the laboratory equipment or at least one electrical device of the laboratory equipment (e.g., a centrifuge drive motor). In particular, it refers to the voltage supplied from outside the laboratory equipment by a power supply network.

[0035] The aforementioned first electrical switch may be the only switch whose switching state is monitored when the power is turned on. The first electrical switch may be, but is not necessarily, the first switch to be turned on. More precisely, in the case of a power supply with a phase conductor and a neutral conductor, preferably, at least the switching state of the switch connected to the phase conductor on the power supply side is monitored. Particularly preferred is that the switching states of all switches are monitored, and this is taken into account by the sequence controller during the switching process.

[0036] The first electrical switch, or at least one electrical switch, can be, for example, a relay or a controllable semiconductor switch, such as a transistor, such as a thyristor, a field-effect transistor, and / or a transistor with an insulated gate electrode, such as an IGBT. In principle, any controllable switch can be used. Therefore, an electrical switch is a controllable electrical switch.

[0037] The monitoring device can signal the presence of the operating voltage to the sequence controller in different ways. For example, when the operating voltage is present, a corresponding signal in the form of a defined signal level can be permanently generated. Alternatively, the presence of the operating voltage can only be temporarily notified by a signal, such as a pulse signal. Furthermore, the absence of a defined signal or the failure to generate a signal can also indicate the presence of the operating voltage. This also applies if the operating voltage is not present. In particular, even if possible, the presence and absence of the operating voltage do not necessarily have to be indicated by the same type of signal; for example, a permanent signal with a high signal level could indicate the presence of the operating voltage, and a permanent signal with a low signal level could indicate its absence.

[0038] As mentioned earlier, during the sequential controller control process, the process of turning on the first and second switches can be a process of turning on the power supply of laboratory equipment.

[0039] The operation of laboratory equipment can be prevented by a sequence controller in various ways. In particular, at least one of the following measures or any meaningful combination of these measures can be performed: resetting (resetting) the process controlled by the sequence controller to a defined state, particularly the initial state; not turning on other switches; turning off one or more switches, particularly all power switches; not enabling operation of at least one and preferably all electrical appliances within the laboratory equipment; and issuing a request to another controller and / or user to stop and / or not initiate operation of the laboratory equipment.

[0040] Specifically, the first and second electrical switches can be turned on independently of each other, and the sequence controller is configured to sequentially turn on the first and second electrical switches when the laboratory equipment is started. Monitoring and executing the turn-on process can be more safely achieved by monitoring the switch states of both switches and sending signals of the corresponding switch states to the sequence controller. On the other hand, if both switches are turned on simultaneously and / or if, before sequentially turning on the switch to be turned on later, it is not checked whether the switch to be turned on first is actually on, and whether the switch to be turned on later has not yet been turned on, both switches may still be turned on erroneously, or, in the case of a power supply with a phase conductor and a neutral conductor, the phase conductor switch may be on while the neutral conductor switch is not. This can lead to ignition sparks. This error may also exist in the monitoring of the switch states, and when the switches are turned on simultaneously, the error may be detected too late. If at least one of the switches is also faulty, an undesirable switch state may occur. Therefore, such a switching process is not as reliable as a process in which switches are switched on sequentially and the expected switching state is checked before and after switching on based on the signal notification of their switching state.

[0041] As described above, in particular, at least two switches will be installed / will be installed, which will be turned on to connect the power supply. Furthermore, as mentioned, preferably, at least one electrical switch is installed / will be installed in each wire of the laboratory equipment, which is necessary for operation of the power supply. In the case of a power supply with a neutral conductor and a single-phase line, at least one switch is therefore installed / will be installed for each of these two lines. In the case of a power supply with more than one phase line, at least one switch is installed / will be installed for each phase line. This applies to all variations of the power supply when the preferred embodiment with first and second electrical switches is discussed below.

[0042] Preferably, the monitoring device is connected / will be connected to the second electrical switch via a third contact on the device side, and connected / will be connected to a potential different from the second potential via a fourth contact on the power supply side. Here, the monitoring device is configured / will be configured to determine the on / off state of the second electrical switch when an electrical operating voltage exists between the third and fourth contacts, and to notify the sequence controller of this state signal. Furthermore, the sequence controller is configured / will be configured to...

[0043] - When the second electrical switch is expected to be off, but the monitoring device signals the on / off state of the first electrical switch, or

[0044] -When the second switch is expected to be turned on, but the monitoring device signals that the first switch is off,

[0045] Prevent the operation of the laboratory equipment. Regarding the method of operating the laboratory equipment, the sequence controller can be operated accordingly, and in the mentioned cases, the operation of the laboratory equipment can be prevented.

[0046] Specifically, the monitoring device and sequence controller can optionally be designed in the exact same manner as the first electrical switch in terms of monitoring and the activation of the second electrical switch. As previously mentioned, the second electrical switch can also be the switch that is activated before the first electrical switch when power is switched on to the laboratory equipment.

[0047] The above-described implementation with a third and fourth contact is a realization of the preferred principle for monitoring two switches, as mentioned earlier.

[0048] The sequence controller can be configured to / will be configured to or will operate accordingly.

[0049] When the monitoring device sends a first predetermined state signal, including the first electrical switch being closed, to the sequence controller, the process for turning on the first electrical switch is initiated.

[0050] Then check whether the monitoring device has sent a signal to the sequence controller indicating the on / off state of the first electrical switch, and

[0051] - If the monitoring device does not send a signal indicating that the first electrical switch is on, it prevents the operation of the laboratory equipment or stops the process controlled by it.

[0052] The process of initiating the connection of the first electrical switch can be, in particular, controlled and / or triggered connection. The first predefined state can be determined solely by the switching state of the first electrical switch. Preferably, particularly as described above, if more than one switch in the switching device is monitored for its switching state, the first predetermined state of the electrical switching device is determined by the switching states of the multiple switches in the switching device. Thus, for example, if the first electrical switch is the switch to be connected later in a two-switch sequence, the first predetermined state requires that the other switch, which was connected earlier, has already been connected. On the other hand, if the first electrical switch is the switch to be connected first in a two-switch sequence, the first predetermined state requires that the other switch, which is to be connected later, is open. Specifically, as described above, the third and fourth contacts can be used to monitor the switching state of the second electrical switch.

[0053] The monitoring device may include a detection device, specifically for monitoring the switching state of each electrical switch to be monitored. This detection device is configured / will be configured to determine the on / off state of the electrical switch when an electrical operating voltage exists between the two contacts and to signal this state to the sequence controller. As will be described in more detail below, the two contacts need not be a pair of contacts where one contact is located on the equipment side of the electrical switch and the other on the power supply side, as mentioned above. More precisely, the switching states of two electrical switches in different lines of the power supply (e.g., neutral conductor and phase line) of laboratory equipment can also be monitored using a single detection device. Here, only the on / off state of both switches on one side and the other state on the other side can be distinguished. The other state is that at least one of the two switches is off.

[0054] Particularly preferred is to monitor the switching states of both electrical switches in this manner, and additionally (as already described) separately monitor the switching state of at least one of the two electrical switches. In this case, monitoring means, as mentioned several times, signaling the corresponding state to the sequence controller, and this state is preferably also taken into account when determining whether the process to be controlled by it should continue. Thus, at least one of the switches is redundantly monitored for its switching state. This allows the sequence controller to check the functionality of the monitoring device to determine faults. Particularly preferred is that, in the event of a fault, the process controlled by the sequence controller is interrupted, aborted, and / or prevented from operating the laboratory equipment.

[0055] Therefore, laboratory equipment can be configured / will be configured, or will operate accordingly, as follows:

[0056] The monitoring device has a first detection device configured to determine the on / off state of a first electrical switch and notify the sequence controller of this state signal when an electrical operating voltage exists between a first contact and a second contact.

[0057] The monitoring device is connected to the first electrical switch via the fifth contact on the device side, and to the second electrical switch via the sixth contact on the device side.

[0058] The monitoring device includes a third detection device configured to determine the on / off state of the first and second electrical switches when an electrical operating voltage exists between the fifth and sixth contacts, and to notify the sequence controller of this state signal.

[0059] - The sequence controller is configured to prevent the operation of the laboratory equipment or stop the process controlled by it if it is not notified of the corresponding on state by either the first detection device or the third detection device after the first and second electrical switches are turned on.

[0060] Specifically, the sequence controller can also check whether the first and third detection devices send signals indicating the corresponding on / off status within a predetermined time period. If this is not the case, the sequence controller can prevent the operation of the laboratory equipment or stop the process it controls. In this way, in particular, malfunctions of the monitoring devices can be detected through the sequence controller.

[0061] Specifically, a second detection device can also be configured to determine the on / off state of the second electrical switch when an electrical operating voltage exists between the third and fourth contacts and to notify the sequence controller of this state signal. In this case, if the sequence controller is not notified of the corresponding on / off state by either the first, second, or third detection device after activating the first and second electrical switches, it will prevent the operation of the laboratory equipment or stop the process controlled by it. This makes the error detection and monitoring device more reliable.

[0062] The monitoring device may have at least one device having at least one bistable trigger. At least when the bistable trigger is connected to its power supply, one of the two possible states of the bistable trigger is maintained stably until a condition for state change is met. A commonly used bistable trigger has a data input and a trigger input. If a trigger signal is received at the trigger input, for example, if the level of the input signal changes at the trigger input, a state change can occur if a corresponding change in the data signal also occurs at the data input. Specifically, the data signal can then be switched to the output of the bistable trigger as it exists at the data input (or inverted in another embodiment).

[0063] Preferably, the logic for process control within the sequential controller is implemented in hardware, and more preferably only in hardware. The hardware of the logic circuit can, in particular, include logic gates, bistable flip-flops and Schmitt triggers, as well as classic electronic components such as resistors, capacitors, and diodes. The advantage of hardware logic over software logic is that it does not require a new license, unlike software updates which typically necessitate such updates. If the hardware logic meets the requirements and fulfills its function, no updates are needed.

[0064] Specifically, the aforementioned process for powering on the laboratory equipment can be implemented at least in part by the hardware logic of a sequence controller. According to one embodiment, the sequence controller has electronic circuitry with a bistable trigger, wherein the bistable trigger is connected to a first signal line on the input side, and a monitoring device sends a signal to the bistable trigger via this first signal line indicating that a first electrical switch has been turned on. On the output side, the bistable trigger is connected to a second signal line, through which the bistable trigger sends a signal, based on a signal transmitted via the first signal line and based on another signal, indicating that the power-on process for the laboratory equipment can continue through the sequence controller or that the power-on process has been successfully completed.

[0065] Another signal, particularly in the aforementioned implementation of the bistable trigger, is present or exists at the trigger input. Without a trigger signal, the signal on the first signal line (i.e., the data line) is not (unchanged or reversed) sent to the output. Typically, not only with embodiments having data and trigger inputs, further signals may depend on the fact that a start signal for initiating a process controlled by a sequence controller is available or has been given, and / or a signal indicating successful execution of a previous process step (e.g., turning on another electrical switch) has been generated.

[0066] A bistable trigger is a fundamental logic element related to the process flow. Specifically, the evaluation of signals from the aforementioned detection device can be implemented in this way. In this case, the implementation does not involve a first electrical switch, but rather a second electrical switch or two electrical switches, which are jointly monitored by a single detection device. Therefore, the bistable trigger can be connected to a first signal line on its input side, through which the monitoring device sends a signal indicating that the first and second electrical switches are turned on.

[0067] In an advantageous embodiment, the further signal (particularly the signal at the trigger input) also depends on whether the bistable trigger is signaled by the monitoring device to the on state of the first electrical switch. Therefore, if the monitoring device does not receive a signal indicating an on state, this prevents the bistable trigger from signaling at its output that the connection process for activating the laboratory equipment can continue through the sequence controller or that the connection process was successful. Thus, the bistable trigger only signals that the connection process for activating the laboratory equipment can continue through the sequence controller, or that the connection process was successful if the first switch was actually activated. This avoids errors in the sequence controller that could occur if there is a fault in the switch to be activated and a fault in the bistable trigger. In particular, a drawback in the bistable trigger may be the continuous detection of a signal at the data input indicating the on state of the electrical switch. In the above-described embodiment with a trigger input, a defective switch prevents the bistable trigger from receiving a trigger signal that would enable the signal to be output at its signal output.

[0068] According to a further embodiment, the sequence controller may have a test apparatus with a simulation device configured to simulate the first electrical switch being de-energized for the control process of the sequence controller executing a control process that turns on the first electrical switch when the simulation device is activated. As previously mentioned, the electrical switch need not be the first switch to be turned on. It is also possible to simulate the de-energization of corresponding switches for multiple electrical switches. Here, the test apparatus is configured / will be configured to check, when the simulation device is activated, whether the sequence controller is capable of enabling the laboratory equipment after the control process has run. If, when the simulation device is activated, the prerequisites for enabling the operation of the laboratory equipment are concluded to be met, the test apparatus sends an error signal to the sequence controller. In particular, the error signal indicates that operation has not been enabled. In the case where the sequence controller is implemented via hardware logic, the test apparatus can be implemented, for example, by adding logic gates. If a test signal is subsequently provided to one or more logic gates, for example, at the start of the control process to be executed by the sequence controller, this will activate the simulation.

[0069] This invention relates to laboratory equipment containing flammable refrigerants. While not falling within the scope of the appended claims, the invention can be applied to other equipment and apparatus, particularly those also containing flammable refrigerants. This means that switching devices, monitoring devices, and sequential controls are also present in the embodiments described herein. Attached Figure Description

[0070] Exemplary embodiments and further embodiments of the invention will now be described with reference to the accompanying drawings. In the various figures of the drawings:

[0071] Figure 1A schematic diagram of a laboratory apparatus using a flammable refrigerant, featuring electrical connections and a cooling system, is shown.

[0072] Figure 2 A first embodiment of the electrical switching equipment, monitoring device, and sequence controller is shown.

[0073] Figure 3 A second embodiment of the electrical switching equipment, monitoring device, and sequence controller is shown.

[0074] Figure 4 A third embodiment of the electrical switching equipment, monitoring device, and sequence controller is shown.

[0075] Figure 5 A first circuit arrangement with a bistable trigger is shown.

[0076] Figure 6 A second circuit arrangement with a bistable trigger is shown.

[0077] Figure 7 A third circuit arrangement with a bistable trigger is shown.

[0078] Figure 8 A fourth circuit arrangement with a bistable flip-flop is shown, and

[0079] Figure 9 The circuit layout with two bistable flip-flops is shown. Detailed Implementation

[0080] Figure 1 The laboratory equipment 1, schematically shown, has an electrical connection 3, as indicated by the two diagonal lines, which has two wires. Specifically, this could be a neutral conductor and a phase conductor. Alternatively, the laboratory equipment may have electrical connections with more than one phase conductor, such as a three-phase connection.

[0081] Laboratory equipment 1 also includes an electrical switch device 5. Devices 10 and 11 to be supplied with electrical energy, such as centrifuge motors and centrifuge controllers, can be switched on by turning on the switch device 5. Figure 1 The switch shown is connected to an external power source.

[0082] The electrical switch assembly 5 is combined with a monitoring device 7 and a sequence controller 8. The monitoring device 7 is used to monitor the electrical switch assembly 5. The sequence controller 8 is used to control at least one process to be performed at the start and / or during operation of the laboratory equipment 1. In particular, the process controlled by the sequence controller 8 is specifically related to the power supply of the laboratory equipment. The sequence controller 8 receives signals from the monitoring device 7 during its operation.

[0083] Furthermore, laboratory equipment 1 has a cooling device 13 that uses a flammable refrigerant. The cooling effect produced during the operation of the cooling device 13 is indicated by multiple downward-pointing arrows. The cooling device 13 can also be powered from an external power source via a switching device 5, for which the electrical switch of the switching device 5 must be turned on. In contrast, the monitoring device 7 and the sequence controller 8 are powered independently of the switching state of the switching device 5. A separate power source can be provided for this purpose, but it is preferably also powered by the aforementioned external power source.

[0084] Figure 2 It shows Figure 1 The first embodiment of the electrical switching device 5 or a corresponding switching device for another laboratory device. The external power supply, and therefore the switching device 5, has a first wire 3a (e.g., neutral conductor N) and a second wire 3b (e.g., phase wire). For example, the external power supply can operate on a public power supply network with a corresponding available voltage and grid frequency, such as 230V and 50Hz as per German standards.

[0085] Electrical switch SW_N is located in the first wire 3a. Another electrical switch SW_L is located in the second wire 3b. With both switches open, the device requiring external power during laboratory equipment operation is disconnected from the power supply and therefore cannot operate. To operate the equipment, both electrical switches SW_N and SW_L must be turned on.

[0086] In this embodiment, the monitoring device 7 has a single detection device W_L, designed to monitor the switching state of the switch SW_L in the second wire 3b. The detection device W_L is connected to the electrical switch SW_L in the second wire 3b on the device side via a first contact 21, and to a potential different from the potential of the second wire 3b on the power supply side via a second contact 22. This other potential is the potential of the first wire 3a. The second contact 22 is therefore located on the power supply side of the electrical switch SW_N in the first wire 3a. The detection device W_L has an optocoupler, for example, as in other implementations. If an electrical operating voltage is thus present between contacts 21 and 22, the optocoupler generates a corresponding signal indicating the on / off state of the switch SW_L in the second wire 3b. This signal is fed to the sequence controller 8. When the switch SW_L in the second wire 3b is on, the electrical operating voltage exists only between contacts 21 and 22. Otherwise, the potential at the first contact 21 is not at the potential of the phase line of the external power supply.

[0087] The sequence controller 8 controls the connection of two electrical switches SW_N and SW_L via corresponding actuators S_N and S_L. The corresponding control circuits of the switches, such as the control circuits of relays, are activated by the actuators when appropriately manipulated by the sequence controller 8.

[0088] Figure 3 It shows Figure 1 The second embodiment is of the electrical switching device 5 or a corresponding switching device of another laboratory device. This embodiment can be applied to the same power supply having two power supply lines 3a, 3b, such as... Figure 1 and Figure 2 For example, a power supply line may consist of a phase conductor and a neutral conductor, as indicated by the letters L and N.

[0089] and Figure 2 Compared to the first embodiment, the monitoring device 7 is expanded with two additional detection devices W_N and W_LN. The detection device W_LN and... Figure 1 The same situation exists and it has the same contacts 21, 22 as power supply lines 3a, 3b. However, in the connection line of the detection device W_L, a diode 28 is also provided, which, together with two other diodes 29, 30 in the connection lines of the two other detection devices W_N and W_LN of the second power supply line 3b, prevents unintentional current flow that may occur in the connection chain between the two power supply lines 3a, 3b. To prevent such unintentional current flow, another diode 30 can also be omitted. However, their use is preferred for achieving symmetry in the circuit arrangement. Since the embodiment is an AC power supply, current flow occurs through the connection lines in the corresponding on state of the switch or only in one half-wave of each cycle of the power supply voltage. However, this is sufficient for the detection devices W_L, W_N, and W_LN (e.g., they are then implemented by optocouplers respectively) to determine the on state.

[0090] The detection device W_N is connected to the third contact 23 of the first power supply line 3a on the equipment side and to the fourth contact 24 of the second power supply line 3b on the power supply side via its two connecting lines. Therefore, it is designed to determine the switching state of the electrical switch SW_N in the first power supply line 3a.

[0091] The detection device W_LN is connected via its two connecting lines to the fifth contact 25 of the first power supply line 3a on the equipment side and to the sixth contact 26 of the second power supply line 3b on the power supply side. Therefore, it is configured to determine the switching states of two switches, namely the electrical switch SW_N in the first power supply line 3a and the electrical switch SW_L in the second power supply line 3b. As mentioned above, it can only determine whether both switches are on or whether at least one of the switches is off. The functionality and advantages of this additional detection device have been discussed.

[0092] Figure 4 A third embodiment of the electrical switching device 37 of the laboratory equipment is shown, wherein the electrical switching device 37 differs from... Figure 1The electrical switching device 5 has three phase lines 3a, 3b, and 3c. Switching device 37 has switches SW_1, SW_2, and SW_3 in each of the three phase lines. Sequence controller 39 controls the connection of the three electrical switches via corresponding actuators S_1, S_2, and S_3. The corresponding control circuits for the switches, such as relay control circuits, are activated by the actuators when properly manipulated by the sequence controller 39.

[0093] and Figure 3 Compared to the illustration of the second embodiment of the electrical switching device 5, this illustration is simplified. Specifically, the connection lines of the monitoring device 38 to the diodes in the power supply line are not shown, although they are... Figure 3 This situation exists. This is for clarity of illustration. Furthermore, for greater clarity, the connection lines of monitoring device 38 are also shown as single lines, although there are two connection lines. This is represented by two diagonal lines extending parallel to each other. Diagonal lines are drawn when only the connection lines are represented.

[0094] In a third exemplary embodiment, the monitoring device 38 has three detection devices, which are not shown separately for clarity. Each of these detection devices is connected to two contacts in three power supply lines 3a, 3b, and 3c via its connecting line, and is connected to one contact on the device side of a switch in one power supply line and to one contact on the power supply side in another power supply line. For example, the first detection device is connected to the first power supply line 3a via the first contact 31 on the device side of switch SW_1, and to the third power supply line 3c via the second contact 32 on the power supply side of the third switch SW_3.

[0095] Optionally, at least one additional detection device may be present, which can determine the common energized state of two of the three switches. This additional detection device will be connected to the two switches to be monitored on the device side via a contact respectively.

[0096] Alternative or additional land, Figure 4 The arrangement shown can be extended to a three-phase current supply with a neutral conductor by a detection device capable of determining the on / off state of the switches in the neutral conductor.

[0097] Figure 5 The circuit shown can be part of the execution logic in the hardware of a sequential controller, such as the sequential controller in one of the foregoing embodiments. The circuit has a logic gate 43 and a bistable flip-flop 41. The bistable flip-flop 41 has a data input D and a trigger input T. It also has an output OUT for outputting its output signal.

[0098] In the exemplary embodiment shown, two input signals L_WN and L_WL are fed to logic gate 43. Input signal L_WN, for example, reflects... Figure 2 or Figure 3 The switching state of the electrical switch SW_N in the first power supply line 3a of the embodiment. The input signal L_WL, for example, reflects the switching state of the electrical switch SW_N. Figure 3 The switching state of the electrical switch SW_L in the second power supply line 3b of the embodiment. Through additional circuit elements (not shown), such as additional logic gates and / or Schmitt triggers, the input signals L_WN and L_WL can be interconnected and / or linked to other signals in different ways before being fed to the inputs of the logic gates, depending on the circuit design. All signals are preferably signals with two possible states, such as a low signal level state and a high signal level state. Binary logic can be implemented in this way.

[0099] For example, in the embodiment described below, input signals L_WN and L_WL are linked together and logic gate 43 is configured such that when both input signals L_WN and L_WL have low signal levels, logic gate 43 outputs a signal with a high signal level. A low signal level in input signals L_WN and L_WL in this case means the switch is closed. Alternatively, input signals L_WN and L_WL are linked together, for example, and logic gate 43 is configured such that when both input signals L_WN and L_WL have high signal levels, logic gate 43 outputs a signal with a high signal level. In this case, a high signal level in input signals L_WN and L_WL means the switch is closed. To achieve this, for example, the signal generated by the detection device reflecting the switching state of the corresponding switch can be reversed.

[0100] In the embodiment described herein, a start signal L_ST can be fed to logic gate 43, specifically at the start of a process controlled by a sequence controller for turning on two electrical switches. The start signal includes a change from a low signal level to a high signal level at the trigger input T of the bistable trigger 41. Before receiving the start signal, the output OUT of the bistable trigger 41 is at a low signal level. The start signal L_ST enables the input signal at the data input D of the bistable trigger 41 to switch to its output OUT. As described above, because logic gate 43 outputs a signal with a high signal level to the data input D when both switches are closed, and because the high signal level at the output OUT is interpreted as the expected state in the switching device composed of the first and second switches, a logic circuit for checking the closed state of the two switches is implemented. If the check is successful, i.e., a high signal level appears at the output OUT of the bistable trigger 41, the next step in the process controlled by the sequence controller is thus initiated.

[0101] Now refer to Figure 6The circuit shown describes such a next step or a step that will be performed later in the process. This circuit is related to... Figure 5 The circuit shown differs only in that the bistable flip-flop is indicated by reference numeral 51 and the logic gate is indicated by reference numeral 53. Furthermore, the bistable flip-flop 51 is fed a signal L_T at its trigger input. This is generally understood as the trigger signal, i.e., the signal that enables the bistable flip-flop 53 to change the state of its output signal at output OUT according to the input signal currently present at data input D.

[0102] To execute the next step, the input signals L_WN and L_WL can be processed before they are fed to the input of logic gate 53, or they can be received as is by the corresponding detection device and passed to logic gate 53, such that input signal L_WN has a high signal level when the switch in the first power supply line is on, and input signal L_WL has a high signal level when the switch in the second power supply line is off. Furthermore, logic gate 53 is configured to output a high-level signal when both input signals are high.

[0103] Trigger signal L_T, for example, according to Figure 5 The output signal at the output OUT of the bistable trigger 41 is generated. Alternatively or additionally, the trigger signal L_T can be triggered when the detection device determining the switching state of at least one electrical switch outputs a corresponding signal. Therefore, in particular, the above reference Figure 5 The signal change described, from a low signal level to a high signal level, or the signal change of another device indicating a corresponding state change, can trigger [the change]. Figure 6 The possible signal changes at the output OUT of the bistable multivibrator 51 are considered. If a high signal level appears at the data input D of the bistable multivibrator 51 at this time, that is, the switch in the first power supply line is turned on and the switch in the second power supply line is turned off, then a signal change occurs at the output OUT of the bistable multivibrator 51, changing from a previously existing low signal level to a high signal level. In this way, it can be determined that the switch in the first power supply line has been turned on during this period.

[0104] The previous mention of the "next step" in the process controlled by the sequence controller refers to the next step of checking the status of the switching equipment. However, it was also mentioned that the switch in the first power supply line has been turned on simultaneously. This can be described as the next step in the entire control process. Then, refer to... Figure 5 The steps in the described process will be the next step after that, or the next step if further steps are performed in between.

[0105] In order to Figure 6The signal level at the output OUT of the bistable multivibrator 51 changes at the correct time, and the trigger signal L_T can arrive at the trigger input T with a delay. This is achieved, for example, using classic circuit components such as resistors, capacitors, and diodes. The use of such circuit components for this purpose is well-known and will not be described in detail here. Due to the delay, for example, the electrical switch in the first power supply line can be pre-connected. The switching process requires a corresponding time period, and the delay of the trigger signal L_T is set to that time period.

[0106] Figure 7 It shows Figure 6 The circuit shown is modified as follows: The output of logic gate 63 is connected to one input of additional logic gate 65. The other input of additional logic gate 65 is connected to the signal line of the trigger signal L_T. The output of additional logic gate 65 is connected to the trigger signal input T.

[0107] Therefore, in the previous reference Figure 6 In the described implementation, the signal at the trigger input T also depends on the on / off state of the electrical switch to be monitored, as signaled by the monitoring device to the bistable trigger 61. Therefore, the bistable trigger only signals that the step of turning on the electrical switch is successful when the switch is actually turned on. Errors that can be eliminated in this way have been described. Therefore, in the event of these errors, the output signal of the bistable trigger 61 will not be incorrectly set to a high signal level, and the erroneous process can be prevented from continuing.

[0108] However, Figure 7 The principle of the circuit shown is not limited to checking the on / off state of the switch in the first power supply line. More precisely, it can be used to check any expected state occurring within the hardware logic. Furthermore, the logic gate can have additional inputs, so that, in particular, the signal on the trigger input T can also depend on the signal state of other signals. Furthermore, with reference to the above... Figure 5 and Figure 6 Similar to the circuit described, the signal level on the input side of the bistable multivibrator can be selected differently depending on the expected state, and / or the output signal of the bistable multivibrator can be given at a low signal level to indicate that the expected state has been determined.

[0109] Figure 8 Further modifications to the circuit described so far are shown. Such modifications may also be provided in addition to those already described. Figure 8 The modification shown is that the logic gate 73, whose output is connected to the data input D of the bistable flip-flop 71, receives three input signals L_WN, L_WL, and L_WNL. These can be signals related to the switching state of the switch (optionally associated with and / or inverted with other signals), in... Figure 3In the case of the circuit layout, these signals are generated by the detection device.

[0110] In particular, Figure 8 The modifications can be checked based on the configuration and / or preprocessing of signals regarding the switch status.

[0111] All three detection devices simultaneously sent a signal that both switches were off.

[0112] Two of the three detection devices simultaneously send a signal that a specific switch (the first switch or the second switch) is turned on.

[0113] - All three detection devices consistently sent a signal that both switches were turned on.

[0114] However, preferably, particularly, no check is performed regarding whether the detection device consistently sends signals indicating that one or both switches are on, or not merely by... Figure 8 The circuit shown is used to perform this. More precisely, it preferably corresponds to... Figure 9 The circuit shown illustrates the circuit principle. Here... Figure 9 The circuit shown is presented in a simplified form. In particular, logic gates are omitted, and only two bistable flip-flops 81 and 83 are shown as hardware logic elements.

[0115] The circuit principle is that the input signal of the data input of one bistable flip-flop is used as the input signal of the trigger input of another bistable flip-flop, and vice versa. Therefore, an input signal is fed through signal lines to the data input D of one bistable flip-flop and the trigger input T of another. As mentioned above, additional logic switching elements, such as elements for inverting signals, can also be used here. Furthermore, in particular, one of the two input signals can be the output signal of a logic gate that logically links two primary input signals (e.g., signals from two different detection devices in a monitoring device) together.

[0116] In the specific embodiment shown, an input signal, such as signal L_WL, represents Figure 3 The switching state of the switch in the second power supply line 3b, while another input signal, such as signal L_WNL, represents... Figure 3 The switching states of the switches in the first and second power supply lines 3a and 3b. Alternatively, for example, in another embodiment, the input signal L_WL can be replaced by linking signals representing the switching states of one of the two switches respectively.

[0117] A change in the signal level of one of the signals can trigger a possible change in the output signal of the corresponding bistable trigger. Figure 9 The circuit principle can error-free evaluate the redundancy information of various detection devices. In this sense, redundancy information is particularly important, if... Figure 3 In this case, a detection device is provided to individually signal the switch status of at least one electrical switch, and a detection device is also provided to signal the common on / off status of two switches.

[0118] Furthermore, a time tolerance between the presence of two input signals (e.g., signals L_WL, L_WNL) is preferably allowed. This can be achieved by delaying the signal level change at the corresponding trigger input T, as described above, for example using discrete circuit components such as at least one resistor and capacitor, and at least one diode to reduce the voltage of the charging capacitor. Thus, the signal level change of the input signal initially causes the capacitor to charge, and then discharges again over time. At some point during the discharge process, the signal level change occurs at the trigger input T.

Claims

1. Laboratory device (1) with flammable refrigerant, wherein the laboratory device (1) has: - an electrical connection (3) for providing electrical energy for the laboratory device (1), wherein the laboratory device (1) can be connected to at least two different potentials of a power supply network for its operation via the connection (3), - an electrical switching device (5) with a first electrical switch for electrical separation from a first potential of the at least two different potentials and a second electrical switch for electrical separation from a second potential of the at least two different potentials, - a sequence controller (8) configured to switch on the first electrical switch (SW_L) and the second electrical switch (SW_N), - a monitoring device for monitoring the electrical switching device (5), wherein the monitoring device is connected to the first electrical switch (SW_L) via a first contact on the device side and to another potential than the first potential via a second contact on the power supply side, wherein the monitoring device is configured to determine the switching state of the first electrical switch (SW_L) when an electrical operating voltage is present between the first contact and the second contact and to signal this state to the sequence controller (8), wherein the sequence controller (8) is configured to - prevent the operation of the laboratory device (1) when the first electrical switch (SW_L) is expected to be switched off, but it is signaled by the monitoring device that the first electrical switch (SW_L) is switched on, or - prevent the operation of the laboratory device (1) when the first electrical switch (SW_L) is expected to be switched on, but it is signaled by the monitoring device that the first electrical switch (SW_L) is switched off. The first and second electrical switches can be switched on independently of each other, and wherein the sequence controller (8) is configured to switch on the first electrical switch and the second electrical switch in succession when starting the operation of the laboratory device (1).

2. The laboratory equipment according to claim 1, wherein, the monitoring device is connected to the second electrical switch via a third contact on the device side and to a potential different from the second potential via a fourth contact on the power supply side, 3. Laboratory equipment according to claim 1 or 2, wherein wherein the monitoring device is configured to determine the switching state of the second electrical switch when an electrical operating voltage is present between the third contact and the fourth contact and to signal this state to the sequence controller (8), wherein the sequence controller (8) is configured to - prevent the operation of the laboratory device (1) when the second electrical switch is expected to be switched off, but it is signaled by the monitoring device that the first electrical switch is switched on, or - prevent the operation of the laboratory device (1) when the second electrical switch is expected to be switched on, but it is signaled by the monitoring device that the first electrical switch (SW_L) is switched off.

4. Laboratory device according to claim 1, wherein the sequence controller (8) is configured to - start a process for switching on the first electrical switch (SW_L) when the monitoring device sends a first predetermined state signal of the electrical switching device (5) including the first electrical switch switched off to the sequence controller, - start a process for switching on the second electrical switch (SW_N) when the monitoring device sends a second predetermined state signal of the electrical switching device (5) including the second electrical switch switched off to the sequence controller. ​ - it is then checked whether the monitoring device has signaled to the sequence controller that the first electrical switch (SW_L) is in the on state, and - if the monitoring device has not signaled the on state of the first electrical switch (SW_L), the operation of the laboratory device (1) is prevented or a process controlled by the sequence controller is stopped.

5. Laboratory device according to claim 1, wherein - the monitoring device has a first detection device (W_L, W_N) which is configured to determine the on state of the first electrical switch (SW_L) and to signal this state to the sequence controller (8) when an electrical operating voltage is present between the first contact and the second contact, - the monitoring device is connected to the first electrical switch (SW_L) via a fifth contact on the device side and to the second electrical switch via a sixth contact on the device side, - the monitoring device has a third detection device (W_LN) which is configured to detect the on state of the first electrical switch (SW_L) and the second electrical switch and to signal this state to the sequence controller (8) when an electrical operating voltage is present between the fifth contact and the sixth contact, and - the sequence controller (8) is configured to prevent the operation of the laboratory device (1) or to stop a process controlled thereby if it is not signaled by the first detection device and by the third detection device after switching on the first electrical switch (SW_L) and the second electrical switch that the respective on state.

6. The laboratory equipment of claim 1, wherein, The sequence controller (8) has a test device with an analog device which is configured to simulate that the first electrical switch is not on for the control process of the sequence controller (8) which switches on the first electrical switch (SW_L) when the analog device is activated, wherein the test device is configured to check, with the analog device activated, whether the sequence controller (8) can enable the laboratory device (1) to run after the control process has run, and wherein the test device signals an error to the sequence controller (8) if the sequence controller (8) enables the laboratory device (1) to run with the analog device activated.

7. The laboratory equipment of claim 1, wherein, The sequence controller (8) has an electronic circuit with a flip-flop, wherein the flip-flop is connected on the input side to a first signal line via which the monitoring device sends a signal to the flip-flop to switch on the first electrical switch, and wherein the flip-flop is connected on the output side to a second signal line via which the flip-flop sends a signal for the switching-on process of the laboratory device (1) to be continued by the sequence controller (8) or for the switching-on process to be successful depending on the signal transmitted via the first signal line and depending on a further signal.

8. The laboratory equipment according to claim 7, wherein, The further signal also depends on the fact that the on state of the first electrical switch (SW_L) is signaled to the flip-flop by the monitoring device.

9. A method for operating a laboratory device (1) with a flammable refrigerant, wherein The laboratory device (1) has: - an electrical connection (3) for providing the laboratory device (1) with electrical energy, wherein the laboratory device (1) can be connected to at least two different potentials of a power supply network for its operation via the connection (3), - an electrical switching device (5) having a first electrical switch for electrically separating from a first potential of the at least two different potentials and a second electrical switch for electrically separating from a second potential of the at least two different potentials, - a sequence controller (8) configured to switch on the first electrical switch and the second electrical switch, - a monitoring device for monitoring the electrical switching device (5), wherein the monitoring device is connected to the first electrical switch via a first contact on the device side and to another potential than the first potential via a second contact on the power supply side, wherein the monitoring device determines the switching state of the first electrical switch (SW_L) when an electrical operating voltage is present between the first contact and the second contact and signals this state to the sequence controller (8), and wherein the sequence controller (8) - prevents the operation of the laboratory device (1) when the first electrical switch is expected to be switched off, but it is signaled by the monitoring device that the first electrical switch (SW_L) is switched on, or - prevents the operation of the laboratory device (1) when the first electrical switch is expected to be switched on, but it is signaled by the monitoring device that the first electrical switch (SW_L) is switched off. The first and second electrical switches can be switched on independently of each other, and wherein the sequence controller (8) switches on the first electrical switch and the second electrical switch in succession when starting the operation of the laboratory device (1).

10. The method of claim 9, wherein, The monitoring device is connected to the second electrical switch via a third contact on the device side and to a potential different from the second potential via a fourth contact on the power supply side, 11. The method of claim 9 or 10, wherein, wherein the monitoring device determines the switching state of the second electrical switch when an electrical operating voltage is present between the third contact and the fourth contact and signals this state to the sequence controller (8), wherein the sequence controller (8) - prevents the operation of the laboratory device (1) when the second electrical switch is expected to be switched off, but it is signaled by the monitoring device that the first electrical switch (SW_L) is switched on, or - prevents the operation of the laboratory device (1) when the second electrical switch is expected to be switched on, but it is signaled by the monitoring device that the first electrical switch (SW_L) is switched off. The sequence controller (8) - starts a process for switching on the first electrical switch (SW_L) when the monitoring device sends the sequence controller a first predetermined state signal of the electrical switching device (5) including the first electrical switch being switched off, 12. The method of claim 9, wherein, - then checks whether the monitoring device has signaled to the sequence controller that the first electrical switch (SW_L) is in the switched-on state, and - prevents the operation of the laboratory device (1) or stops a process controlled thereby if the monitoring device has not signaled the first electrical switch (SW_L) being in the switched-on state.

13. The method according to claim 9, wherein: ​ ​ - the monitoring device has a first detection device (W_L) which determines the on state of the first electrical switch (SW_L) and signals this state to the sequence controller (8) when an electrical operating voltage is present between the first contact and the second contact, - the monitoring device is connected to the first electrical switch via a fifth contact on the device side and to the second electrical switch via a sixth contact on the device side, - the monitoring device has a third detection device (W_LN) which determines the on state of the first electrical switch (SW_L) and the second electrical switch and signals this state to the sequence controller (8) when an electrical operating voltage is present between the fifth contact and the sixth contact, and - the sequence controller (8) prevents the operation of the laboratory device (1) or stops the process controlled thereby if it is not signalled by the first detection device nor by the third detection device that the respective on state has been achieved after switching on the first electrical switch (SW_L) and the second electrical switch.

14. The method of claim 9, wherein, The sequence controller (8) has a test device with a simulation device which, when activated, simulates for the control process executed by the sequence controller (8) that the first electrical switch (SW_L) is not on when the simulation device is activated, wherein the test device checks, with the simulation device activated, whether the sequence controller (8) can enable the laboratory device (1) to run after the control process has run, and wherein the test device issues an error signal to the sequence controller (8) if the sequence controller (8) can enable the laboratory device (1) to run with the simulation device activated.

15. A method for manufacturing a laboratory apparatus (1) having a flammable refrigerant, wherein The laboratory device is provided with - an electrical connection (3) for providing the laboratory device (1) with electrical energy, wherein the laboratory device (1) can be connected to at least two different potentials of a power supply network via the connection (3) for its operation, - an electrical switching device (5) having a first electrical switch for electrical separation from a first potential of the at least two different potentials and a second electrical switch for electrical separation from a second potential of the at least two different potentials, - a sequence controller (8) which is configured to switch on the first electrical switch and the second electrical switch, - a monitoring device for monitoring the electrical switching device (5), wherein the monitoring device is connected to the first electrical switch via a first contact on the device side and to another potential than the first potential via a second contact on the power supply side, wherein the monitoring device is configured to determine the on state of the first electrical switch (SW_L) and to signal this state to the sequence controller (8) when an electrical operating voltage is present between the first contact and the second contact, wherein the sequence controller (8) is configured such that the sequence controller - is signalled by the monitoring device that the first electrical switch (SW_L) is on when the first electrical switch is expected to be off, or - when it is expected that the first electric switch is turned on, but it is signaled by the monitoring device that the first electric switch (SW_L) is in the off state, Preventing the operation of the laboratory equipment (1).

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